Kleifarvatn is one of the largest lakes in the country, about 8 km² in size and 136m above sea level. The maximum depth in the lake is about 90m, with an average depth of about 29m. The Hafnarfjörður angling club handles the fishing rights. The lake contains both Arctic char and brown trout and is known for big fish. Records show that there are a lot of fish in the lake and divers have seen good numbers of fish there. The Hafnarfjörður angling club has started a breeding program for the lake and in recent years they have released juveniles into it. Trails around the lake have been repaired.